Amanda Knox stabbed Meredith Kercher to death after the British student accused the American of taking money from her room, an Italian court has said.

The appellate court in Florence made public a 337-page document on Tuesday explaining the new guilty verdicts issued to Knox and her Italian former boyfriend Raffaele Sollecito in January.

The pair were convicted in January following an appeal, three years after they had been originally cleared of the brutal killing.

The court noted at least two knives were used to attack Ms Kercher and that there were finger imprints on her body which indicated she had been held down.

The document said: "It is a matter of fact that at a certain point in the evening events accelerated; the English girl was attacked by Amanda Marie Knox, by Raffaele Sollecito, who was backing up his girlfriend, and by Rudy Hermann Guede, and constrained within her own room."

Image Caption:Meredith Kercher was studying in Italy as part of her degree at Leeds

But judges said there was "no evidence to suggest the killing has been as the result of a sex game" - the motive which was originally used to convict them at their first trial in 2009.

In his conclusion, judge Alessandro Nencini said the 21-year-old had been murdered as a "result of the progression of aggression and a desire to humiliate Meredith".

He added that "Amanda and Meredith had no reciprocal sympathies towards each other" and that "the presence of all three at the crime scene was proved by their traces in the blood of the victim".

Under police questioning, Guede made a statement saying Ms Kercher had blamed Knox for taking money from her room in the apartment they shared in Perugia.

After the document was released, Knox said the court's reasoning was unsupported by "evidence of logic".

"I want to state again today what I have said throughout this process; I am innocent of the accusation against me, and the recent motivation document does not - and cannot - change the fact of my innocence," she said.

The release of the court's reasoning could mean the verdict is sent to the Court of Cassation. If it upholds the convictions, authorities could begin an extradition process to bring Knox back to Italy.

Sollecito's lawyer, Giulia Bongiorno, was critical of the reasoning, saying "from the motive, to weapon, to the DNA, it is a string of errors".

"I can't wait until they fix a day to hear us for the appeal, because honestly the verdict is so full of errors, illogical elements and contradictions, that I strongly believe it will be overturned."

Ms Kercher, from Coulsdon, Surrey, was found dead in her apartment on November 2, 2007. Her throat had been slashed and she had been sexually assaulted.

Knox and Sollecito were arrested four days later and served four years in prison before they were acquitted by an appeals court in 2011.

The high court in Italy overturned that acquittal and ordered a new trial. Knox was sentenced to 28 and a half years in prison and Sollecito for 25 years in January.

Guede was convicted in a separate trial and was jailed initially for 30 years - reduced to 16 after an appeal.